Im stuck on these three engines for my revo 2.5r upgrade/basher build.

1.http://www.amainhobbies.com/product_...e-w-Pull-Start

2.http://www.amainhobbies.com/product_...e-w-Pull-Start

3.http://www.amainhobbies.com/product_...in-Start-Combo

I really dont wanna have to do a ton of work to get one of these to fit but I don't think it will be that bad and if anyone could recommend a pipe and header that would be awesome thanks guys